Lab Report Scaffold: Bromination Of Trans-Cinnamic Acid

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Chem 51 LB Experiment 3 Report Scaffold: Bromination of Trans-Cinnamic Acid 1. The goal of this experiment was to perform a halogenation reaction through the addition of two bromides from pyridinium tribromide. This was accomplished by reacting trans-cinnamic acid with pyridinium tribromide. After the reaction took place, melting point analysis was conducted to find out the stereochemistry of the product, which could either be syn-addition, anti-addition, or syn + anti-addition. 2. Vacuum filtration was performed on the crude product, then it was recrystallized for purification. Melting point analysis was conducted on the recrystallized product to determine its identity. 3. The three possible mechanisms in this experiment were syn-addition …show more content…

The product obtained was (2S, 3R)-2, 3-dibromo-3-phenylpropanoic acid and (2R, 3S)-2, 3-dibromo-3-phenylpropanoic acid, which are enantiomers. This was determined through melting point analysis. The melting point range for the product was 198 to 202 degrees Celsius, which is a lot close to the given melting point of the anti-addition product, 202-204 degrees Celsius. The given melting point range was 93.5-95 degrees Celsius. Furthermore, the syn-addition product is unlikely and difficult to produce due to stereochemistry selectivity. 9. The melting point range was lower than the given range of the anti-addition product by 2 degrees Celsius. This could have been due to impurities in the product. A likely cause could have been water that still remained in the product after recrystallization (the product shifted upward during melting point analysis due to evaporation). Since water has a low melting point, it could have lowered the melting point range of the product. However, 2 degrees Celsius is not extremely significant to pronounce inconclusiveness of the …show more content…

Yes, the melting point data does make sense. While the melting point range was close to the given temperature range, the data was still a little lower than expected. This may have been caused by impurities in the product, since impurities cause melting point range to decrease. The product was observed moving up the capillary tube during melting point analysis, which indicates that the product was not completely dry before melting point range was taken. The water in the product evaporated and caused the product to be pushed up. It can be hypothesized that the water in the product affected the melting point

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